HyperText Transfer Protocol (HTTP) Live Streaming (also known as HLS) is an HTTP-based media streaming communications protocol. It works by breaking the overall stream into a sequence of small HTTP-based file downloads, each download loading one short chunk of an overall potentially unbounded transport stream. As the stream is played, the client may select from a number of different alternate streams containing the same material encoded at a variety of data rates, allowing the streaming session to adapt to the available data rate. At the start of the streaming session, it downloads an extended M3U playlist containing the metadata for the various sub-streams which are available.
In a typical live streaming scheme, the content key that is used to decrypt the media content on the player device is delivered over secure HTTP (HTTPS), which is a combination of HTTP with Secure Sockets Layer (SSL), a cryptographic protocol that provides communication security over the internet.
Most Digital Rights Management (DRM) systems provide services such as proximity checking or copy protection enforcement that go beyond what is provided by SSL. HTTPS is deemed not to be effective enough to implement live streaming in a DRM-based system. Therefore, the above problem calls for a DRM-based system to securely deliver media content keys to player devices.